It is proposed to continue studies concerned with the disposition of the volatile anesthetics, halothane, enflurane, and isoflurane. Recent studies of halothane in our laboratory indicate that a metabolite of it binds irreversibly to phospholipids while another metabolite binds to protein. That metabolite which binds to phospholipids is an abnormal metabolite. We plan to pursue the study of this binding to determine what role this binding plays in the hepatotoxicity sometimes seen following the use of this agent. Halothane hepatitis has been produced in rats in our laboratory and in addition a plasma factor has been found in these animals which may be useful in studying the mechanism of cell injury in chemically induced hepatitis. This factor may also be useful in diagnosing this type of liver injury, something which is not presently available. Enflurane and isoflurane are two other agents we propose to study in detail to determine if either of these agents undergo abnormal metabolism. All three agents will be studied to determine if any metabolite is mutagenic or carcinogenic. Studies are also planned to determine if metabolites bind to DNA and RNA. The studies will include isolation, purification and characterization of proteins involved in the binding and the cytotoxic factor. The studies will include in vitro, isolated hepatocyte, isolated perfused organs and in vivo preparations. Guided by the results of the animal studies we plan to pursue these investigations in isolated human hepatocytes. These will be isolated from human hepatic tissues obtained at autopsy.